In communications systems, there may be a challenge to obtain good performance and capacity for a given communications protocol, its parameters and the physical environment in which the communications system is deployed.
An example of applications available in some communications system is group communications services. In general terms, group communication means that the same information or media is delivered to multiple client nodes (as hosted by wireless devices).
In group communication systems the client nodes receiving the same media constitute a group of client nodes. These client nodes may be located at different locations in a radio coverage area served by one or more radio access network nodes. If many client nodes are located within the same area, the one or more radio access network nodes could use multicast or broadcast based transmission using e.g., Multicast-Broadcast Multimedia Services (MBMS) for efficient communication to the group of client nodes since communications resources, such as time and frequency resources, are shared among the client nodes.
Some activities are performed before MBMS can be used. One activity involves an MBMS bearer to be activated. This will enable media to be sent over the network and broadcasted over the radio network to the client nodes. In a third generation partnership program (3GPP) Long Term Evolution (LTE) network this is initiated in a Broadcast Multicast Service Center (BMSC) as discussed in document 3GPP TS 23.246 v14.0.0. Another activity is to inform the client nodes of the service being broadcasted over the MBMS bearer. This activity is performed in order for the client nodes to know how to receive the media over the MBMS bearer. This procedure is commonly known as a service announcement procedure and is discussed, e.g., in document 3GPP TS 26.346 v14.0.0 which relates to service announcement in LTE networks.
MBMS provides a one-way communication channel, meaning that the data is broadcasted from a radio access network node towards wireless devices hosting client nodes. When a wireless device that receives data over an MBMS bearer is moving closer to the border of the broadcast area of the MBMS bearer in the radio access network node, the wireless device will request to receive the group communication data over a unicast bearer instead of as before via broadcast.
However, there is a risk that the MBMS bearer is suspended or otherwise interrupted. Suspension of MBMS bearer could cause problems not only for the client nodes but for the communications system as a whole. MBMS bearers are examples of multicast bearers.
Hence, there is still a need for an improved handling of interruptions of multicast bearers.